I know all these different forms of protection but what is the difference between all of them?

TCUs and Aliens are SLCDs, which are spring loaded camming devices (the catch-all name for cams.) TCUs are 3-lobed cams made by Metolius (though some people use this as a name for other 3-lobed cams), and Aliens are a specific brand made by CCH, known for being especially good in placements where some other brands aren't.

I know all these different forms of protection but what is the difference between all of them?

SLCD = Spring Loaded Caming Device. It refers to all cams (including TCUs and Aliens) that we use as climbers, but we usually don't refer to them as such.

TCU = Three Cam Unit. This is a cam that has three lobes instead of the traditional 4. While I suposse any brand cam with three lobes could technically be called a TCU, people are usually refering to the brand Metolious and their three cam units when talking TCUs.

Aliens = simply a brand of cams. Originally made by CCH, now made by Fixe. Other examples are Camalots made by black Diamond and Master Cams made by Metolious.

There tricams though... I don't think they should be called a "cam" because they can be used passively just fine and simply are tricams. They can use a camming motion but I woulnd't say, "Hey hand me 3 cams" meaning tricams.

There tricams though... I don't think they should be called a "cam" because they can be used passively just fine and simply are tricams. They can use a camming motion but I woulnd't say, "Hey hand me 3 cams" meaning tricams.

Even hexes have a camming mode. SLCD refers to camming devices with moving parts - it doesn't matter if they can also be placed passively. To whine that all cams are not SLCDs because tricams aren't is belabored semantic nit-picking.

Even hexes have a camming mode. SLCD refers to camming devices with moving parts - it doesn't matter if they can also be placed passively. To whine that all cams are not SLCDs because tricams aren't is belabored semantic nit-picking.

Isn't belabored semantic nit-picking what the internet, and in particular, rc.com is for?

As for hexes vs tricams -- I find that I almost always place a tricam in a cammed placement (so think of them as cams), I have yet to make a hex placement that is cammed (and I do carry and place hexes).

There tricams though... I don't think they should be called a "cam" because they can be used passively just fine and simply are tricams. They can use a camming motion but I woulnd't say, "Hey hand me 3 cams" meaning tricams.

Even hexes have a camming mode. SLCD refers to camming devices with moving parts - it doesn't matter if they can also be placed passively. To whine that all cams are not SLCDs because tricams aren't is belabored semantic nit-picking.

Most informed reply so far. Research "active" v. "passive". Research Choiunard catalogs from the 70's.